Using orchard for multiple website applications

I have 3 different website which deals with its own business functionality. Is it a good idea to creat these as orchard modules and share the common orchard home page? What are the points I need to consider before hosting my websites under orchard modules?
Will there be any performance issue when orchard loads these big web sites under module?

Sorry,
Ignore that statement. I have 5 different websites handling its different business requirements (eg, document management, payroll website etc). Can I use orchard and add these websites as modules so that i can get a single portal and have integrated home page.
Is there any chance of performance or other issues?

I see. Well, you certainly could rebuild these 5 websites as 5 Orchard modules, each implementing the various business requirements, but don't expect these websites to just work when you turn them into a module. I can't say anything about performance or
other issues as I know nothing about your current websites, but at the very least expect a learning curve you'll go through (which is only normal I suppose).